<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			body {
				/* min-width: 550px; */
				/* 2x leftContent width + rightContent width */
				font-weight: bold;
				font-size: 20px;
				margin: 0;
				padding: 0;
			}

			.header,
			.footer {
				background-color: purple;
				text-align: center;
				color: white;
				line-height: 60px;
				clear: both;
			}
			.center{
				padding: 0 200px;
				background-color: #00FFFF;
				overflow: hidden;
			}
			.column{
				height: 240px;
				float: left;
				position: relative;
			}
			#left{
				width: 200px;
				background-color: red;
				margin-left: -200px;
				left: -100%;
			}
			#right{
				width: 200px;
				margin-left: -200px;
				right: -200px;
				background-color: palevioletred;
			}
			#content{
				width: 100%;
				background-color: #4CD213;
			}
			
		</style>
	</head>
	<body>
		<div class="header">这是头部</div>
		<div class="center">
			<div class="column" id="content">这是中间内容的中间盒子</div>
			<div class="column" id="left">这是中间内容的左边盒子</div>
			<div class="column" id="right">这是中间内容的右边盒子</div>
		</div>
		<div class="footer">这是底部</div>
	</body>
</html>
